Rusty Bowtie
General Category => General Discussion - Intros => Topic started by: munch on December 10, 2015, 02:07:07 PM
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
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Back in the day when I was working for GM we had a problem with the converter not unlocking when it was beginning to fail which would act like a standard transmission coming to a stop without pushing the clutch in causing the engine to stall. If your using lock up that could be a possibility. If your running it through a toggle switch try leaving it turned off and if your running it through the internal 4th gear pressure switch you can just pull the connector off of the transmission as it only controls the converter. Drive the car with it disconnected and see what happens.
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Back in the day when I was working for GM we had a problem with the converter not unlocking when it was beginning to fail which would act like a standard transmission coming to a stop without pushing the clutch in causing the engine to stall. If your using lock up that could be a possibility. If your running it through a toggle switch try leaving it turned off and if your running it through the internal 4th gear pressure switch you can just pull the connector off of the transmission as it only controls the converter. Drive the car with it disconnected and see what happens.
DITTO
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Back in the day when I was working for GM we had a problem with the converter not unlocking when it was beginning to fail which would act like a standard transmission coming to a stop without pushing the clutch in causing the engine to stall. If your using lock up that could be a possibility. If your running it through a toggle switch try leaving it turned off and if your running it through the internal 4th gear pressure switch you can just pull the connector off of the transmission as it only controls the converter. Drive the car with it disconnected and see what happens.
Thanks Moose and Ed,
That is exactly the way mine acts. The man that built my trans has passed away, but I do know that there is an electrical wire running from the left back of the trans to the fuse box. Should I disconnect that and drive it?
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That is exactly the way mine acts. The man that built my trans has passed away, but I do know that there is an electrical wire running from the left back of the trans to the fuse box. Should I disconnect that and drive it?
munch...That should be the connection for the converter. Go ahead and disconnect it and give it a try.
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That's the same symptoms I had when I first put mt 33 together. I unplugged it and it went away. Converter was staying locked.
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Attached a diagram, I believe with a GM harness the fused 12v power wire to the transmission is light blue.
The transmission shifts the gears hydraulically, when it levels out the the torque converter solenoid locks up the torque converter via the constant 12v wired to it. It stays locked up until you push the brake pedal, which opens the circuit (no power to solenoid) and the torque converter unlocks.
If your pedal adjustment is off when you stop - the power to the transmission may continue and you will have the same symptoms as if you didn't push in the clutch pedal on a stick shift car.
You can run the car without 12v to the tranny, but it's not recommended. The intent of the lock-up is to reduce internal transmission wear and reduce torque converter temperature.
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Attached a diagram, I believe with a GM harness the fused 12v power wire to the transmission is light blue.
The transmission shifts the gears hydraulically, when it levels out the the torque converter solenoid locks up the torque converter via the constant 12v wired to it. It stays locked up until you push the brake pedal, which opens the circuit (no power to solenoid) and the torque converter unlocks.
If your pedal adjustment is off when you stop - the power to the transmission may continue and you will have the same symptoms as if you didn't push in the clutch pedal on a stick shift car.
You can run the car without 12v to the tranny, but it's not recommended. The intent of the lock-up is to reduce internal transmission wear and reduce torque converter temperature.
Ed,
I did replace my inline brake light switch with a manual lever type at the brake pedal because I wanted the brake lights to come on sooner. I wonder if I messed something up there.
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The torque converter will unlock when coming to a stop whether or not the break switch is working because it's primary control is the 4th gear pressure switch as show in the wiring diagram. The converter in only commanded on in forth. I'm not using a brake switch in my 32 with a 700 and it works fine. It is possible that you have a defective 4th gear pressure switch that is not opening which can be easily tested with an ohm meter. As far as running without the converter hooked to 12 volts causing a problem with the transmission, unless you have an early transmission it will not cause a problem as GM redesigned the oil supply system on the later transmissions to allow more oil flow through the transmission cooler and and also supplying more flow to critical components during non lockup conditions. Jef Lynch GM engineer had a good post on our site on the subject that should help in understanding the issue...Here is a quote.
First, TV cable adjustment is easy, it's TV installation that must be right. The cable must be perpendicular to the throw of the throttle arm pickup point, and it must swing in the proper arc. So if you use late model Quadrajet that was used with a 700R4 or a 200R4 you're ok. If you run a Holley or an AFB (Edelbrock) style carb you will have to purchase and install a cable corrector bracket. Once you get the cable happy just set it so that it is tight a wide open throttle and adjust it back and forth a click at a time until you get the shift points where you want them. If you have to go more than a few clicks then it I time to start modifying the governor springs, or changing the governor itself to a Corvette style and changing springs on that. I can give you more if you need it. If you run an E transmission, such as a 4L60E then you don't have these issues.
More on this later if you need further explanation.
Can I run without the converter clutch locked. The answer is a definitive YES if your trans is a 1985 or later, and if your hotrod is light weight and you aren't into delivering Abrahm's tanks the the early ones are ok, too. The only time you can run into trouble because of not locking the converter is if you have a heavy vehicle, under a constant heavy load, with a marginal cooler. Again, you should run trans temp gauge if you red worried about overheating the transmission. If you run n E trans it incorporates a thermistor in the internal switch plate which can be read through the controller or scan tool. The post 1984 transmissions routed more cooler oil through the radiator when then TCC is engaged.
The wiring for the TCC is something you have to know from the builder. I wire all of the transmissions I sell with the grounding switch in the fourth gear circuit of the valve body providing ground. I don't need or want the TCC on until fourth. If you look at 700 wiring schematics you won't believe how many different schemes the factory had over the years. To operate the clutch you should need to provide B+ to I the correct terminal on the trans! I always use the right front terminal, interrupted by the brake switch, and I some cases a vacuum switch. But the vacuum switch needs to be adjustable because every car is different and every driver want something different. For those reasons I tend to not use the vacuum switch. You can have a TCC circuit that works electrically and hydraulically that doesn't seem to work which could be for a worn out clutch disc a failed converter, or maybe just the little I seal on the turbine (input) shaft. You can check to see if the circuit is working by connecting a pressure gage into a cooler line and watching for about a 25 psi pressure drop when I the TCC is commanded on.
These explanations are going to raise a bunch of questions, and that's good. And my typing isn't all that good on this iPad, so I am going to use the computer for now on!!
If you are going to build your own transmission I recommend Transgo kits. They have the TV circuit down to science and when you re done it works perfectly. If you want to keep from getting covered with trans fluid from modifying governors the consider an E transmission.
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[/quote] Ed,
I did replace my inline brake light switch with a manual lever type at the brake pedal because I wanted the brake lights to come on sooner. I wonder if I messed something up there.
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If it worked before...might look at it again.
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
Just wondering..did you try unplugging the power?
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
Just wondering..did you try unplugging the power?
Ed,
I plan on doing this on Saturday and I'll be sure to let you know.
Thanks
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
Just wondering..did you try unplugging the power?
I unplugged the power and test drove it, the same thing happened. If I make it out of the neighborhood without stalling, it levels out after everything warms up. It is like no matter how warm the engine is, it has to be driven to get the transmission warm and acting right.
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
Just wondering..did you try unplugging the power?
I unplugged the power and test drove it, the same thing happened. If I make it out of the neighborhood without stalling, it levels out after everything warms up. It is like no matter how warm the engine is, it has to be driven to get the transmission warm and acting right.
Are you confident that the tranny is the problem and it's not a fuel delivery problem?
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I have a 200R4 in my car and it want to stall the engine when it downshifts coming to a STOP. In warmer weather, it seems to correct itself after a short distance. When it is cooler, it takes longer. I read something about the RPMs staying up as it downshifts. Is this a function of the torque converter?
Just wondering..did you try unplugging the power?
I unplugged the power and test drove it, the same thing happened. If I make it out of the neighborhood without stalling, it levels out after everything warms up. It is like no matter how warm the engine is, it has to be driven to get the transmission warm and acting right.
Are you confident that the tranny is the problem and it's not a fuel delivery problem?
I just redid the fuel pump last year with hoses and a Holley red. What are you thinking?
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Are you confident that the tranny is the problem and it's not a fuel delivery problem?
[/quote] I just redid the fuel pump last year with hoses and a Holley red. What are you thinking?
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Maybe somebody else might jump in but if the trans was the problem I would think that the problem would be there even if the tranny was cold? It appears that the situation is more like the symptoms of a choke cold idle issue? Now that the weather outside is cooler is the situation more evident than it was during Summer?
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One more thing that you might consider is the valve body in the transmission. I have seen where a sticking valve can cause any number of conditions that might act like the engine is being pulled down due to incorrect shifting points or late downshifts. If the TV valve is sticking it can cause all sorts of problems one of which is incorrect part throttle downshift. Make sure you have the correct geometry at the carburetor to control the cable and valve. The best way to test TV and valve body functions is with a pressure gauge. I don't know how familiar you are with the TV system on the 200r4 but here's a link to Bowtie Overdrives that goes into great detail on the subject.It might be worth a look
Bowtie Overdrives TV 101 (http://www.tvmadeez.com/article/)
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I am running a Bowler Tru-Shift system https://bowlertransmissions.com/p/64/tru-shift-throttle-correction-arm-system
I have also sent them a question about this. Like I said it disappears after a few miles, so it doesn't keep me from driving, just annoying.